SURFACE-PROPERTIES AND INTERFACIAL ADHESION STUDIES OF ARAMID FIBERS MODIFIED BY GAS PLASMAS

The surface of aramid (Kevlar 49) fibre was modified by NH3, O-2 or H2 O plasmas in order to improve the adhesion to epoxy resin. Electron sp ectroscopy for chemical analysis (ESCA) and static secondary ion mass spectroscopy (SSIMS) were used to identify the chemical compositions a nd functional groups of the plasma-treated fibre surface, respectively . The surface topography and mechanical properties of plasma-treated f ibres were also investigated. After plasma treatments, the interfacial shear strength (IFSS) of aramid-fibre/epoxy-resin composites, as meas ured by the microbond pull-out technique, was markedly improved (43-83 % improvement) and the fibre strength was only little affected (less t han 10% loss). Significant improvement in the IFSS principally resulte d from forming the covalent bonds between the newly reactive functiona lities at the modified fibre surfaces and the epoxides of the resin.